Rotor assembly for vertical shaft air preheater

ABSTRACT

A rotor for an air preheater that comprises a vertical rotor post surrounded by a series of independent sector-shaped baskets. The baskets are each supported by the rotor post at a plurality of axially displaced locations radially outboard from the rotor post. Gravity acting upon each basket produces a force couple at the points of support whereby the uppermost point is in direct tension and the lowermost point is in direct compression thereby placing the load at the ends of the rotor post and obviating the necessity of a massive rotor post structure between points of support. Differential thermal deformation of the rotor and the rotor post will produce only a slight repositioning of related elements without producing cracking and failure of a rigid connecting bone therebetween.

United States Patent [1 1 [111 3,891,029 Mahoney June 24, 1975 ROTOR ASSEMBLY FOR VERTICAL SHAFT AIR PREHEATER Primary Examiner-Albert W. Davis, Jr. Attorney, Agent, or Firm-W. l-l. Lang ABSTRACT A rotor for an air preheater that comprises a vertical rotor post surrounded by a series of independent sector-shaped baskets. The baskets are each supported by the rotor post at a plurality of axially displaced locations radially outboard from the rotor post. Gravity acting upon each basket produces a force couple at the points of support whereby the uppermost point is in direct tension and the lowermost point is in direct compression thereby placing the load at the ends of the rotor post and obviating the necessity of a massive rotor post structure between points of support. Differential thermal deformation of the rotor and the rotor post will produce only a slight repositioning of related elements without producing cracking and failure of a 10 Claims, 4 Drawing Figures [75] Inventor: Robert E. Mahoney, Wellsville, NY.

[73] Assignee: The Air Preheater Company, Inc., [57] Wellsville, NY.

[22] Filed: Feb. 4, 1974 [21] Appl. No.: 439,506

[52] US. Cl 165/8; 165/10 [51] Int. Cl. F28d 19/00 [58] Field of Search 165/8, 10, 9

[56] References Cited UNITED STATES PATENTS 2,981,521 4/1961 Evans et a1. 165/8 X 3,216,486 11/1965 Hall et a1. 165/8 X 3,267,562 8/1966 Chiang et a1 165/8 X 3,391,727 7/1968 Topouzian 165/10 X rigid connecting bone therebetween, 3,710,850 1/1973 Kurschner et a1. 165/10 3,789,916 2/1974 Lindahl 165/8 1 E i 12 5 i I I E i I l l l I E i I l i i I} l i I g I 1 1 1 V l |Trrw I- i 1.- I 1 h I; i i111]- ROTOR ASSEMBLY FOR VERTICAL SHAFT AIR PREI-IEATER BACKGROUND OF THE INVENTION 1. Field of the Invention This application relates to a rotor for a rotary regenerative heat exchanger that is arranged around a vertically disposed rotor post. The rotor is comprised of independent sector-shaped baskets of heat absorbent element that are affixed at a pair of axially spaced locations to the rotor post.

2. Description of Prior Art In a vertical air preheater of conventional design the baskets depending from a central rotor post usually comprise radially disposed diaphragms having a sectorial spacing therebetween forming baskets that are adapted to carry a mass of heat absorbent element. The diaphragms are attached continuously by rigid welding to the rotor post whereby the post must be comprised of a heavy forging or the like capable of supporting the continuously welded member. A rotor so constructed is structurally massive, heavy and therefore expensive because of the excessive amount of material used and welding required. Moreover, such a rotor is subject to premature cracking and failure of weldments because the integrally welded joints are subjected to differential expansion as they traverse various temperature zones.

A similar problem attending the design of horizontal shaft air preheaters has resulted in the development of an air preheater as represented by US. Pat. Nos. 3,710,850 and 3,710,851 both of Jan. 16, 1973. IN these patents a single pivotal joint intermediate each rotor basket and the adjacent rotor post permits relative expansion between a horizontal rotor post and the rotor baskets that depend therefrom. Moreover, in thses patents the total weight of each element basket is carried directly by the central portion of the rotor post making it necessary that the entire rotor post is formed from massive structure having sufficient strength to carry an equivalent deadweight, vertical load.

SUMMARY OF THE INVENTION The present invention is accordingly directed to a rotary regenerative heat exchange device that carries a mass of heat absorbent material alternately between a cold fluid and a hot fluid in order that heat from the hot fluid may be transferred to the cold fluid, and in particular it relates to a rotary regenerative heat exchanger that has a vertical shaft and is adapted to rotate about a vertical axis.

The heat absorbent material is carried in baskets supported by the rotor shaft at the axial ends thereof as a force couple whereby the load at the top of the rotor post is directed radially outward and the load at the bottom thereof is directed radially inward. Thus, only the dead-weight vertical load of the rotor is transmitted axially through the rotor post and as a result, only a thin shell between points of attachment is required.

The rotor is surrounded by a housing formed with end plates at spaced ends that have openings to simultaneously direct a hot fluid and a cold fluid through spaced compartments of the rotor, and it includes a series of independent sector-shaped baskets of element that are supported by the rotor post. The baskets are supported by the rotor post only at their axially disposed ends while the space therebetween remains entirely free from contact to permit relative movement without inducing structural breakage of a weld or other bonding means that may be used to connect the rotor baskets to the rotor post. Moreover, all components of the rotor may be shop fabricated, field work required to assemble the unit is minimized, erection time greatly reduced, and a substantial economy of manufacturing and assembly costs may be realized.

BRIEF DESCRIPTION OF THE DRAWING For a better understanding of the nature and objectives of my invention, reference may be made to the following detailed descriptions taken in conjunction with the accompanying drawing in which:

FIG. 1 is a sectional elevation of a heat exchanger constructed in accordance with the present invention,

FIG. 2 is an enlarged side elevation of a means of attaching an element basket to a rotor post,

FIG. 3 is an enlarged sectional view showing the details of a modified form of basket attachment, and

FIG. 4 is a plan view of a plurality of adjacent rotor sectors.

DESCRIPTION OF THE PREFERRED EMBODIMENT The arrangement of the drawing shows a rotary regenerative heat exchanger having a rotor post 12 supported by bearings 14 disposed for rotation about a vertical axis. The rotor is rotated about its axis by means of a drive motor and suitable reduction gearing 18 that is connected to the rotor post. A mass of heat exchange material 20 is contained in independent, open-ended sector-shaped baskets 22 that are in turn secured to the rotor post. A composite rotor so formed is enclosed by housing 26 that has spaced openings 32, 34, 35 and 37 at opposite ends thereof to direct hot and cold fluids through the heat exchange material in spaced parts of the rotor.

While the entire rotor is constantly subjected to alternating estremes of temperature, it has been found that the inner ends of the element baskets that comprise the portion of the rotor adjacent the rotor post are subjected to maximum temperature variations and therefore maximum thermal expansion and contraction. Moreover, the adjacent rotor post operates in a relatively cool atmosphere so the relative thermal movement between the rotor post and the adjacent rotor is a maximum at the point of connection therebetween.

Thus the usual arrangement of welding the rotor baskets to the rotor post to provide a rigid bond therebetween is unsatisfactory because any connection formed as a rigid weldment will be subjected to a temperature differential, a differential of expansion, a potential cracking of the weldment and failure of the structure. Moreover, inasmuch as such increment of the rotor supports adjacent heavy rotor structure, the rotor post must be made entirely of structurally strong and heavy material so that each increment thereof may support a portion of the rotor.

In accordance with the invention, I provide an arrangement whereby the rotor baskets are secured only to the ends of the rotor post with the intermediate portion of each basket entirely unsecured. Thus the central portion of each rotor basket and the rotor post are free to move relative to one another, and only the ends of the rotor post that actively support the rotor need be constructed of structurally heavy material for connection to the rotor trunnion 38.

Circumferential seals 40 positioned around the end edges of the rotor together with radial seals 42 between adjacent ends of the rotor baskets are adapted to rub against the inner surface of the rotor housing and preclude the flow of fluid therethrough.

The rotor is comprised essentially of a plurality of independent sector-shaped rotor baskets that are each secured at their inner ends to the rotor post and at their outer ends to one another. Each rotor basket includes an upper or tension fitting 44 and a lower or compression fitting 46. The fittings each are sized to fit between the radially extending sides 48 of the individual baskets where they are welded securely thereto to form an integral assembly. The radial inner end of each fitting extends beyond the edge of each basket and is provided with an axially disposed aperture 52 whereby it may be aligned with a matching opening 54 of an upper bracket 56 located on the periphery of the rotor post. After the apertures are aligned they are linked together with a tension pin 62 at the top of the rotor. A similar arrangement is made with a pin linking the fitting 46 and bracket 58 at the bottom of the rotor post.

The upper post fitting 56 and the lower post fitting 58 each comprise an annular member that has a U-shaped configuration adapted to receive the tension fitting 44 and the compression fitting 46. The annular post fittings 56 and 58 may comprise heavy members attached to the outer periphery of the rotor post, or they may be otherwise formed as solid members integral with the rotor post.

The distance d between basket fittings 44 and 46 is somewhat greater than the distance d between post fittings 56 and 58 on the element baskets whereby the distances d and d may vary due to differential expansion or contraction without producing binding or any contact between the interface of the fittings and their respective brackets.

Each post fitting 56 and 58 is U-shaped in order that the pins 62 linking aligned openings in the bracket and engaging fitting are subjected to a double shear force, both above and below their contact with the rotor fittings 44 and 46.

A slight variation from the basic form is shown where the lower or compression fitting is formed with a rubbing surface that is tapered in the manner shown in FIG. 3. The tapered surface on mating members 46 and 58 produces a self-alignment feature that greatly simplifies assembly. Moreover, the taper causes the fittings to be classified as constant strength beams that are well suited to withstand the bending load imposed thereon.

Obviously other modifications and variations of the present invention will become apparent in view of the above teachings, and it is to be understood that equivalent or modified means maybe used freely without resorting to invention. It is also intended that all material shown in the accompanying drawings or described in the accompanying specification shall be interpreted only as illustrative and not in a limiting sense.

I claim:

1. Rotary regenerative heat exchange apparatus having a central rotor post disposed about a vertical axis, a plurality of independent sector-shaped baskets arranged in side-by-side relation to comprise an annular rotor around the rotor post, a mass of heat absorbent material contained in the several baskets of the rotor, housing means surrounding the rotor having inlet and outlet openings that direct a heating fluid and a fluid to be heated through the heat absorbent material of the rotor, means for rotating the rotor about its vertical axis, pivot means for attaching the element baskets to the rotor post comprising a tension fitting connecting the upper extremity of each rotor basket and the rotor post and a compression fitting intermediate the lower extremity of each basket and the rotor post whereby each basket is held in position adjacent the rotor post by a combination of forces transmitted by the tension member and the compression member.

2. Rotary regenerative heat exchange apparatus as defined in claim 1 wherein the means for attaching the upper and lower extremeties of the element baskets to the rotor post comprise radially displaced means that permit each basket to move about an axis that is displaced from the axis of the rotor post.

3. Rotary regenerative heat exchange apparatus as defined in claim 2 including axially displaced pivot means wherein the pivot means moves about an axis that is parallel to the axis of the rotor post.

4. Rotary regenerative heat exchange apparatus as defined in claim 1 wherein the pivot means at the lower end of the rotor comprises a projection that is directed radially inward to direct a compressive force from the element basket, and means on the rotor post adapted to receive the compressive force of said projection and limit its movement radially inward.

5. Rotary regenerative heat exchange apparatus as defined in claim 4 wherein the projection that extends from the bottom of the element basket is tapered about a horizontal axis to mate with the receiving means on the rotor post to simultaneously impart a radial and an axial component of force to the element basket.

6. Rotary regenerative heat exchange apparatus as defined in claim 1 wherein the pivot that extends from the top of the element basket includes a projection that comprises a tie member secured to the element basket including a vertically disposed aperture therein, a fitting on the rotor post, and a shear pin linking the tie member and the fitting on the rotor post to rotatably link the tension fitting to the rotor post.

7. Rotary regenerative heat exchange apparatus as defined in claim 1 wherein the compression fitting comprises an annular fitting including an outward facing groove that surrounds the rotor post.

8. Rotary regenerative heat exchange apparatus as defined in claim 1 wherein the compression fitting comprises an annular fitting that surrounds the rotor post shaped as a frustom of a cone with the base thereof adjacent the bottom of the rotor.

9. Rotary regenerative heat exchange apparatus as defined in claim 1 wherein the tension fitting includes a member having U-shaped configuration that recieves the tie member on the element basket.

10. Rotary regenerative heat exchange apparatus as defined in claim 9 wherein the U-shaped tension member receives the tie member loosely between ends thereof to permit relative axial movement of element baskets and rotor post. 

1. Rotary regenerative heat exchange apparatus having a central rotor post disposed about a vertical axis, a plurality of independent sector-shaped baskets arranged in side-by-side relation to comprise an annular rotor around the rotor post, a mass of heat absorbent material contained in the several baskets of the rotor, housing means surrounding the rotor having inlet and outlet openings that direct a heating fluid and a fluid to be heated through the heat absorbent material of the rotor, means for rotating the rotor about its vertical axis, pivot means for attaching the element baskets to the rotor post comprising a tension fitting connecting the upper extremity of each rotor basket and the rotor post and a compression fitting intermediate the lower extremity of each basket and the rotor post whereby each basket is held in position adjacent the rotor post by a combination of forces transmitted by the tension member and the compression member.
 2. Rotary regenerative heat exchange aPparatus as defined in claim 1 wherein the means for attaching the upper and lower extremeties of the element baskets to the rotor post comprise radially displaced means that permit each basket to move about an axis that is displaced from the axis of the rotor post.
 3. Rotary regenerative heat exchange apparatus as defined in claim 2 including axially displaced pivot means wherein the pivot means moves about an axis that is parallel to the axis of the rotor post.
 4. Rotary regenerative heat exchange apparatus as defined in claim 1 wherein the pivot means at the lower end of the rotor comprises a projection that is directed radially inward to direct a compressive force from the element basket, and means on the rotor post adapted to receive the compressive force of said projection and limit its movement radially inward.
 5. Rotary regenerative heat exchange apparatus as defined in claim 4 wherein the projection that extends from the bottom of the element basket is tapered about a horizontal axis to mate with the receiving means on the rotor post to simultaneously impart a radial and an axial component of force to the element basket.
 6. Rotary regenerative heat exchange apparatus as defined in claim 1 wherein the pivot that extends from the top of the element basket includes a projection that comprises a tie member secured to the element basket including a vertically disposed aperture therein, a fitting on the rotor post, and a shear pin linking the tie member and the fitting on the rotor post to rotatably link the tension fitting to the rotor post.
 7. Rotary regenerative heat exchange apparatus as defined in claim 1 wherein the compression fitting comprises an annular fitting including an outward facing groove that surrounds the rotor post.
 8. Rotary regenerative heat exchange apparatus as defined in claim 1 wherein the compression fitting comprises an annular fitting that surrounds the rotor post shaped as a frustom of a cone with the base thereof adjacent the bottom of the rotor.
 9. Rotary regenerative heat exchange apparatus as defined in claim 1 wherein the tension fitting includes a member having U-shaped configuration that recieves the tie member on the element basket.
 10. Rotary regenerative heat exchange apparatus as defined in claim 9 wherein the U-shaped tension member receives the tie member loosely between ends thereof to permit relative axial movement of element baskets and rotor post. 